U.S. patent application number 12/288184 was filed with the patent office on 2010-04-22 for poly-axial pedicle scre implements and lock screw therefor.
This patent application is currently assigned to Omni SURGICAL, d/b/a SPINE 360, Omni SURGICAL, d/b/a SPINE 360. Invention is credited to Jamie Gottlieb, Kevin Kaufman, Michael Rimlawi, Douglas Won.
Application Number | 20100100136 12/288184 |
Document ID | / |
Family ID | 42109278 |
Filed Date | 2010-04-22 |
United States Patent
Application |
20100100136 |
Kind Code |
A1 |
Won; Douglas ; et
al. |
April 22, 2010 |
Poly-axial pedicle scre implements and lock screw therefor
Abstract
A lock screw assembly for use with a pedicle screw assembly
comprises a lock screw and an upper saddle. The lock screw includes
a fastening tool engaging structure at a first end portion thereof
and an upper saddle receiving structure at a second end portion
thereof. The upper saddle is engaged with the upper saddle
receiving structure of the lock screw in a manner allowing the
upper saddle to rotate about a centerline axis of the lock screw. A
plurality of intersecting spine rod receiving channels extend
through a spine rod engaging portion of the upper saddle in a
manner such that an outwardly-extending spine rod engaging
structure is provided between adjacent ones of the spine rod
receiving channels. Upper and lower surfaces of each spine rod
engaging structure are acutely angled with respect to each other
and wherein a channel edge defined between the surfaces is sharply
pointed.
Inventors: |
Won; Douglas; (Dallas,
TX) ; Kaufman; Kevin; (Fort Worth, TX) ;
Rimlawi; Michael; (Dallas, TX) ; Gottlieb; Jamie;
(Granger, IN) |
Correspondence
Address: |
DAVID ODELL SIMMONS
7637 PARKVIEW CIRCLE
AUSTIN
TX
78731
US
|
Assignee: |
Omni SURGICAL, d/b/a SPINE
360
|
Family ID: |
42109278 |
Appl. No.: |
12/288184 |
Filed: |
October 17, 2008 |
Current U.S.
Class: |
606/301 ;
606/305; 606/308 |
Current CPC
Class: |
A61B 17/7037 20130101;
A61B 2090/037 20160201 |
Class at
Publication: |
606/301 ;
606/305; 606/308 |
International
Class: |
A61B 17/04 20060101
A61B017/04 |
Claims
1. A lock screw assembly for use with a pedicle screw assembly,
comprising: a lock screw including a fastening tool engaging
structure at a first end portion thereof and an upper saddle
receiving structure at a second end portion thereof; and an upper
saddle engaged with the upper saddle receiving structure of the
lock screw in a manner allowing the upper saddle to rotate about a
centerline axis of the lock screw, wherein a plurality of
intersecting spine rod receiving channels extend through a spine
rod engaging portion of the upper saddle in a manner such that an
outwardly-extending spine rod engaging structure is provided
between adjacent ones of said spine rod receiving channels, wherein
upper and lower surfaces of each spine rod engaging structure are
acutely angled with respect to each other and wherein a channel
edge defined between said surfaces is sharply pointed.
2. The lock screw assembly of claim 1 wherein the spine rod
engaging portion of the upper saddle has a generally square end
view profile such that the channel edge defined between said
surfaces are generally straight in said end view.
3. The lock screw assembly of claim 1 wherein the plurality of
spine rod receiving channels consists of two spine rod receiving
channels.
4. The lock screw assembly of claim 3 wherein said two spine rod
receiving channels perpendicularly extend through the second end
portion of the upper saddle.
5. The lock screw assembly of claim 1 wherein the upper surface of
each spine rod engaging structure is downwardly contoured such that
a thickness of each spine rod engaging structure is thinnest at a
tip portion thereof.
6. The lock screw assembly of claim 5 wherein the spine rod
engaging portion of the upper saddle has a generally square end
view profile such that the channel edge defined between said
surfaces are generally straight in said end view.
7. The lock screw assembly of claim 6 wherein: the plurality of
spine rod receiving channels consists of two spine rod receiving
channels; and said two spine rod receiving channels perpendicularly
extend through the second end portion of the upper saddle.
8. A pedicle screw system, comprising: a clamping body including an
axial passage extending between a first end portion and a second
end portion thereof and a spine rod receiving channel extending
through the first end portion of the clamping body in a traverse
direction with respect to the axial passage, wherein a closed end
portion of the spine rod receiving channel is located between said
end portions of the clamping body, wherein a surface of the
clamping body defining the axial passage has threads formed
therein, and wherein said clamping body threads are cupped upwardly
toward the first end portion of the clamping body; and a lock screw
assembly including a lock screw and an upper saddle, wherein the
lock screw is configured for being disposed within the axial
passage of the clamping body with threads thereof matingly engaged
with said clamping body threads, wherein the lock screw includes a
fastening tool engaging structure at a first end portion thereof
and an upper saddle receiving structure at a second end portion
thereof, wherein said lock screw threads are cupped upwardly toward
the first end portion of the lock screw and wherein the upper
saddle is engaged with the upper saddle receiving structure of the
lock screw in a manner allowing the upper saddle to rotate about a
centerline axis of the lock screw.
9. The pedicle screw system of claim 8 wherein: said clamping body
threads and said lock screw threads each include respective spaced
apart load carrying surfaces and a peripheral surface extending
therebetween; said load carrying surfaces of the clamping body are
cupped upwardly toward the first end portion of the clamping body;
and said load carrying surfaces of the lock screw are cupped
upwardly toward the first end portion of the clamping body.
10. The pedicle screw system of claim 9 wherein: perpendicularly
intersecting spine rod receiving channels extend through a spine
rod engaging portion of the upper saddle such that an
outwardly-extending spine rod engaging structure is provided
between adjacent ones of said spine rod receiving channels; and
upper and lower surfaces of each spine rod engaging structure are
acutely angled with respect to each other and wherein a channel
edge defined between said surfaces is sharply pointed.
11. The pedicle screw system of claim 10 wherein the spine rod
engaging portion of the upper saddle has a generally square end
view profile such that the channel edge defined between said
surfaces are generally straight in said end view.
12. The pedicle screw system of claim 11 wherein the upper surface
of each spine rod engaging structure is downwardly contoured such
that a thickness of each spine rod engaging structure is thinnest
at a tip portion thereof.
13. A pedicle screw apparatus, comprising: a clamping body
including an axial passage extending between a first end portion
and a second end portion thereof and a spine rod receiving channel
extending through the first end portion of the clamping body in a
traverse direction with respect to the axial passage, wherein a
closed end portion of the spine rod receiving channel is located
between said end portions of the clamping body, wherein a surface
of the clamping body defining the axial passage has threads formed
therein, and wherein said clamping body threads are cupped upwardly
toward the first end portion of the clamping body; a screw
including a shaft and a semi-spherical shaped head attached to an
end portion of the shaft, wherein the shaft has bone engaging
threads provided along a length thereof and wherein said screw head
is secured within the second end portion of the clamping body in a
manner that limits axial displacement of the screw in a direction
toward the second end portion of the clamping body, that allows
pivoting of the clamping body about said screw head and that allows
rotation of the clamping body about a longitudinal axis thereof; a
lower saddle disposed within the axial passage proximate said screw
head, wherein a screw head engaging surface of the lower saddle has
a mating concave contour to said semi-spherical shape of said screw
head, wherein a spine rod engaging portion of the lower saddle
extends above said closed end portion of the spine rod receiving
channel when the screw head engaging surface of the lower saddle is
engaged with said screw head thereby allowing relative movement
between the screw and the clamping body to be inhibited in response
to a spine rod disposed within the spine rod receiving channel
forcibly urging the lower saddle against said screw head; a lock
screw configured for being disposed within the axial passage of the
clamping body with threads thereof matingly engaged with said
clamping body threads, wherein the lock screw includes a fastening
tool engaging structure at a first end portion thereof and an upper
saddle receiving structure at a second end portion thereof, and
wherein said lock screw threads are cupped upwardly toward the
first end portion of the lock screw; and an upper saddle engaged at
a first end portion thereof with the upper saddle receiving
structure of the lock screw in a manner allowing the upper saddle
to rotate about a centerline axis of the lock screw, wherein
perpendicularly intersecting spine rod receiving channels extend
through a spine rod engaging portion of the upper saddle in a
manner such that an outwardly-extending spine rod engaging
structure is provided between adjacent ones of said spine rod
receiving channels, and upper and lower surfaces of each spine rod
engaging structure are acutely angled with respect to each other
and wherein a channel edge defined between said surfaces is sharply
pointed.
14. The pedicle screw apparatus of claim 13 wherein the spine rod
engaging portion of the upper saddle has a generally square end
view profile such that the channel edge defined between said
surfaces are generally straight in said end view.
15. The pedicle screw apparatus of claim 14 wherein the upper
surface of each spine rod engaging structure is downwardly
contoured such that a thickness of each spine rod engaging
structure is thinnest at a tip portion thereof.
16. The pedicle screw apparatus of claim 13 wherein: said clamping
body threads and said lock screw threads each include spaced apart
load carrying surfaces and a peripheral surface extending
therebetween; said load carrying surfaces of the clamping body are
cupped upwardly toward the first end portion of the clamping body;
and said load carrying surfaces of the lock screw are cupped
upwardly toward the first end portion of the lock screw.
17. The pedicle screw apparatus of claim 16 wherein the spine rod
engaging portion of the upper saddle has a generally square end
view profile such that the channel edge defined between said
surfaces are generally straight in said end view.
18. The pedicle screw apparatus of claim 17 wherein the upper
surface of each spine rod engaging structure is downwardly
contoured such that a thickness of each spine rod engaging
structure is thinnest at a tip portion thereof.
Description
FIELD OF THE DISCLOSURE
[0001] The disclosures made herein relate generally to pedicle
screw assemblies and, more particularly, to saddle configurations
of poly-axial pedicle screw assemblies.
BACKGROUND
[0002] The spinal column is a highly complex system of bones (i.e.,
vertebral bodies) and connective tissues that provides support for
the body and protects the delicate spinal cord and nerves. The
spinal column includes a series of vertebrae stacked one atop the
other, each vertebral body including an inner or central portion of
relatively weak cancellous bone and an outer portion of relatively
strong cortical bone. Situated between each vertebral body is an
intervertebral disc that cushions and dampens compressive forces on
the spinal column. A vertebral canal containing the spinal cord and
nerves is located within the forward-facing surface of the
vertebral bodies.
[0003] There are many types of spinal column disorders. Patients
that suffer from such disorders typically experience extreme and
debilitating pain, as well as diminished nerve function. Examples
of such spinal column disorders include, but are not limited to,
scoliosis (i.e., abnormal lateral curvature of the spine), kyphosis
(i.e., abnormal forward curvature usually in the thoracic portion
of the spine), excess lordosis (i.e., abnormal backward curvature
usually in the lumbar portion of the spine), spondylolisthesis
(forward displacement of one vertebrae over another usually in the
lumbar portion or cervical portion of the spine), etc. There are
still other types of spinal column disorders caused by
physiological abnormalities, disease and/or trauma such as, for
example, ruptured or slipped discs, degenerative disc disease,
fractured vertebra, and the like.
[0004] Multi-segmental spinal fixation is an accepted surgical
procedure in the treatment of such spinal column disorders. It
involves the use of a series of pedicle screw assemblies and one or
more spine rods. The pedicle screw assemblies each include a screw
that is threadedly screwed into one of a plurality of adjacent
vertebral bodies. A spine rod (contoured or straight) is fixedly
secured to a spine rod clamping body of each one of the pedicle
screws for fixing two or more adjacent vertebral bodies in a static
relative position. In this manner, spinal fixation can be used to
alter the alignment of adjacent vertebrae relative to one another
so as to change the overall alignment of the spine, to preclude
relative movement between adjacent vertebrae, and the like.
[0005] The effectiveness of multi-segmental spinal fixation is
dependant on several considerations. Examples of such
considerations include, but are not limited to, the ability of a
pedicle screw assembly to readily and rigidly accommodate a spine
rod bent to the contour of the spine, the ability of a pedicle
screw assembly to reliably secure the bent spine rod in a fixed
position and orientation, the ability of a screw of a pedicle screw
assembly to be threadedly engaged with a vertebral body in a manner
that provides acceptable mechanical strength, and the ability of a
screw of a pedicle screw assembly to be threadedly engaged with a
vertebral body in a manner that minimized adverse deformation
and/or damage to the vertebral body. Known pedicle screw assemblies
are deficient in one or more of these considerations, thus limiting
their effectiveness.
[0006] Therefore, a pedicle screw apparatus, pedicle screw system
and/or a lock screw for use therewith that overcomes deficiencies
associated with known pedicle screw implements would be
advantageous, desirable and useful.
SUMMARY OF THE DISCLOSURE
[0007] Embodiments of the present invention provide for pedicle
screw implements (e.g., a pedicle screw apparatus, pedicle screw
system and/or a lock screw for use therewith) that overcome one or
more deficiencies associated with known pedicle screw implements.
More specifically, pedicle screw implements in accordance with
embodiments of the present invention advantageously impact the
ability of a pedicle screw assembly to readily and rigidly
accommodate a spine rod bent to the contour of the spine, the
ability of a pedicle screw assembly to reliably secure the bent
spine rod in a fixed position and orientation, the ability of a
screw of a pedicle screw assembly to be threadedly engaged with a
vertebral body in a manner that provides superior mechanical
strength, and/or the ability of a screw of a pedicle screw assembly
to be threadedly engaged with a vertebral body in a manner that
minimized adverse deformation and/or damage to the vertebral body.
In doing so, embodiments of the present invention advantageously
impact the implementation and resulting effectiveness of
multi-segmental spinal fixation.
[0008] In one embodiment of the present invention, a lock screw
assembly for use with a pedicle screw assembly comprises a lock
screw and an upper saddle. The lock screw includes a fastening tool
engaging structure at a first end portion thereof and an upper
saddle receiving structure at a second end portion thereof. The
upper saddle is engaged with the upper saddle receiving structure
of the lock screw in a manner allowing the upper saddle to rotate
about a centerline axis of the lock screw. A plurality of
intersecting spine rod receiving channels extend through a spine
rod engaging portion of the upper saddle in a manner such that an
outwardly-extending spine rod engaging structure is provided
between adjacent ones of the spine rod receiving channels. Upper
and lower surfaces of each spine rod engaging structure are acutely
angled with respect to each other and wherein a channel edge
defined between the surfaces is sharply pointed.
[0009] In another embodiment of the present invention, a pedicle
screw system comprises a clamping body and a lock screw assembly.
The clamping body includes an axial passage extending between a
first end portion and a second end portion thereof and a spine rod
receiving channel extending through the first end portion of the
clamping body in a traverse direction with respect to the axial
passage. A closed end portion of the spine rod receiving channel is
located between the end portions of the clamping body. A surface of
the clamping body defining the axial passage has threads formed
therein. The clamping body threads are cupped upwardly toward the
first end portion of the clamping body. The lock screw assembly
includes a lock screw and an upper saddle. The lock screw is
configured for being disposed within the axial passage of the
clamping body with threads thereof matingly engaged with the
clamping body threads. The lock screw includes a fastening tool
engaging structure at a first end portion thereof and an upper
saddle receiving structure at a second end portion thereof. The
lock screw threads are cupped upwardly toward the first end portion
of the lock screw. The upper saddle is engaged with the upper
saddle receiving structure of the lock screw in a manner allowing
the upper saddle to rotate about a centerline axis of the lock
screw.
[0010] In another embodiment of the present invention, a pedicle
screw apparatus comprises a clamping body, a screw, a lower saddle,
a lock screw and an upper saddle. The clamping body includes an
axial passage extending between a first end portion and a second
end portion thereof and a spine rod receiving channel extending
through the first end portion of the clamping body in a traverse
direction with respect to the axial passage. A closed end portion
of the spine rod receiving channel is located between the end
portions of the clamping body and a surface of the clamping body
defining the axial passage has threads formed therein. The clamping
body threads are cupped upwardly toward the first end portion of
the clamping body. The screw includes a shaft and a semi-spherical
shaped head attached to an end portion of the shaft. The shaft has
bone engaging threads provided along a length thereof. The screw
head is secured within the second end portion of the clamping body
in a manner that limits axial displacement of the screw in a
direction toward the second end portion of the clamping body, that
allows pivoting of the clamping body about the screw head and that
allows rotation of the clamping body about a longitudinal axis
thereof. The lower saddle is disposed within the axial passage
proximate the screw head. A screw head engaging surface of the
lower saddle has a mating concave contour to the semi-spherical
shape of the screw head. A spine rod engaging portion of the lower
saddle extends above the closed end portion of the spine rod
receiving channel when the screw head engaging surface of the lower
saddle is engaged with the screw head thereby allowing relative
movement between the screw and the clamping body to be inhibited in
response to a spine rod disposed within the spine rod receiving
channel forcibly urging the lower saddle against the screw head.
The lock screw is configured for being disposed within the axial
passage of the clamping body with threads thereof matingly engaged
with the clamping body threads. The lock screw includes a fastening
tool engaging structure at a first end portion thereof and an upper
saddle receiving structure at a second end portion thereof. The
lock screw threads are cupped upwardly toward the first end portion
of the lock screw. The upper saddle is engaged at a first end
portion thereof with the upper saddle receiving structure of the
lock screw in a manner allowing the upper saddle to rotate about a
centerline axis of the lock screw. Perpendicularly intersecting
spine rod receiving channels extend through a spine rod engaging
portion of the upper saddle in a manner such that an
outwardly-extending spine rod engaging structure is provided
between adjacent ones of the spine rod receiving channels. Upper
and lower surfaces of each spine rod engaging structure are acutely
angled with respect to each other and wherein a channel edge
defined between the surfaces is sharply pointed.
[0011] These and other objects, embodiments, advantages and/or
distinctions of the present invention will become readily apparent
upon further review of the following specification, associated
drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a plan view showing a pedicle screw apparatus in
accordance with an embodiment of the present invention.
[0013] FIG. 2 is a cross sectional view taken along the line 2-2 in
FIG. 1.
[0014] FIG. 3 is a side view of a clamping body for a pedicle screw
apparatus in accordance with an embodiment of the present
invention.
[0015] FIG. 4 is a cross sectional view taken along the line 4-4 in
FIG. 3.
[0016] FIG. 5 is a perspective view of a locking screw assembly for
a pedicle screw apparatus in accordance with an embodiment of the
present invention.
[0017] FIG. 6 is an exploded cross sectional view taken along the
line 6-6 in FIG. 5.
[0018] FIG. 7 is a perspective view showing a lower surface of an
upper saddle for a pedicle screw apparatus in accordance with an
embodiment of the present invention.
[0019] FIG. 8 is a cross sectional view taken along the line 8-8 in
FIG. 7.
DETAILED DESCRIPTION OF THE DRAWING FIGURES
[0020] Pedicle screw implements in accordance with embodiments of
the present invention are used in performing multi-segmental spinal
fixation to alter the alignment of adjacent vertebrae relative to
one another so as to change the overall alignment of the spine, to
preclude relative movement between adjacent vertebrae, and the
like. Advantageously, such pedicle screw implements improve the
effectiveness of multi-segmental spinal fixation. Specifically,
such pedicle screw implements have a construction that enhances
functionality associated with readily and rigidly accommodating a
spine rod bent to the contour of the spine, with reliably securing
the bent spine rod in a fixed position and orientation, with being
threadedly engaged with a vertebral body in a manner that provides
superior mechanical strength, and being threadedly engaged with a
vertebral body in a manner that minimized adverse deformation
and/or damage to the vertebral body. Accordingly, embodiments of
the present invention offer functionality and/or structure that is
advantageous with respect to known pedicle screw implements.
[0021] Referring now to FIGS. 1 and 2, a pedicle screw apparatus
100 in accordance with an embodiment of the present invention is
shown. The pedicle screw apparatus 100 includes a clamping body
102, a screw 104, a lower saddle 106, a lock screw 108 and an upper
saddle 110. As is discussed below in greater detail, the clamping
body 102, the screw 104, the lower saddle 106, the lock screw 108
and the upper saddle 110 are constructed and/or interconnected in a
manner that provides advantageous functionality and/or structure
with respect to known pedicle screw implements.
[0022] Referring to FIGS. 1-3, the clamping body 102 has a first
end portion 112 and a second end portion 114. An axial passage 116
(shown in FIG. 2) extends axially (i.e., along a longitudinal axis
of he clamping body 102) between the first and second end portions
112, 114. A spine rod receiving channel 118 extending through the
first end portion 112 in a traverse direction with respect to the
axial passage 116, thus forming upstanding leg portions 119 of the
clamping body 102. A closed end portion 120 of the spine rod
receiving channel 118 is located between the first and second end
portions 112, 114. A surface 122 of the clamping body that defines
the axial passage 116 has clamping body threads 124 formed
therein.
[0023] Reliefs 126 are provided in an outer surface 128 of the
upstanding leg portions 119 of the clamping body 102. In view of
the reliefs 126, an upper segment 130 of each upstanding leg
portion 119 is frangibly detachable from a lower segment 132
thereof. This frangible functionality provides for ease in engaging
and securing a spine rod 133 within the clamping body 102 (i.e.,
with the upper segments 130 still attached) and for a lower profile
of the implanted pedicle screw apparatus 100 (i.e., with the upper
segments 130 detached).
[0024] Referring to FIGS. 1 and 2, the screw 104 includes a shaft
134 and a semi-spherical shaped screw head 136. The shaft 134
includes a tip portion 138 and an upper end portion 140. The screw
head 136 is attached to the upper end portion 140 of the shaft 134.
The shaft 134 has bone engaging threads 142 provided along a length
thereof. Screws in accordance with the present invention are not
limited to a particular type of thread. However, double lead
threads are a preferred thread for pedicle screw implements in
accordance with embodiments of the present invention. With respect
to single lead threads, it has been found that double lead threads
allow for faster screw insertion while providing for greater pull
out strength and increased fatigue strength at the bone-screw
interface.
[0025] The screw head 136 is secured within the second end portion
114 of the clamping body 102. The screw head 136 is secured in a
manner that limits axial displacement of the screw 104 in a
direction toward the second end portion 114 of the clamping body
102, that allows pivoting of the clamping body 102 about the screw
head 136 and that allows rotation of the clamping body 102 about a
longitudinal axis thereof. For example, in one embodiment of the
present invention, a tip portion 144 of the second end portion 114
has a mating concave contour to the semi-spherical shape of the
screw head 136, thus allowing such relative rotation and pivoting
between the clamping body 102 and the screw 104.
[0026] Referring to FIG. 2, the lower saddle 106 is slideably
disposed within the axial passage 116 proximate the screw head 136.
A screw head engaging surface 146 of the lower saddle 106 has a
mating concave contour to the semi-spherical shape of the screw
head 136. A spine rod engaging portion 148 of the lower saddle 106
(i.e., a generally u-shaped recess) extends above the closed end
portion 120 of the spine rod receiving channel 118 when the screw
head engaging surface 146 is engaged with the screw head 136. In
this manner, relative movement between the screw 104 and the
clamping body 102 is allowed prior to a spine rod being forcibly
urged against the lower saddle by the lock screw 108 and is
inhibited in response to the spine rod 133 disposed within the
spine rod receiving channel 118 being forcibly urged against the
lower saddle 106 by the lock screw 108 thereby causing the screw
head 136 to become clamped between the tip portion 144 of the
clamping body 102 and the screw head engaging surface 146 of the
lower saddle 106. To further promote such inhibited relative
movement, the screw head 136 can include surface texture (e.g.,
circumferential grooves, rough surface, etc) to enhance
friction.
[0027] Referring to FIGS. 2, 5 and 6, the lock screw 108 is
configured for being disposed within the axial passage 116 with
threads 150 thereof matingly engaged with the clamping body threads
124. The lock screw 108 includes a fastening tool engaging
structure 152 at a first end portion 154 thereof and an upper
saddle receiving structure 156 at a second end portion 158 thereof.
A hex socket is a preferred embodiment of the fastening tool
engaging structure 152.
[0028] As best shown in FIGS. 2 and 6, the lock screw threads 150
are cupped upwardly toward the first end portion 154 of the lock
screw 108. As best shown in FIG. 2, the clamping body threads 124
are cupped upwardly toward the first end portion 112 of the
clamping body 102. The clamping body threads 124 include spaced
apart load carrying surfaces 156, 158 and a peripheral surface 160
extending therebetween, as shown in FIG. 2. Similarly, as best
shown in FIGS. 5 and 6, the lock screw threads 150 include spaced
apart load carrying surfaces 162, 164 and a peripheral surface 166
extending therebetween. More specifically, with respect to the
cupped thread configuration, the load carrying surfaces 156, 158 of
the clamping body 102 are cupped upwardly toward the first end
portion 112 of the clamping body 102 and the load carrying surfaces
i 62, 164 of the lock screw 108 are cupped upwardly toward the
first end portion of the lock screw 108.
[0029] The cupped configuration of the lock screw threads 150 and
the clamping body threads 124 advantageously enhance stability of
the upstanding leg portions 119 when force is exerted thereon by
the lock screw 108. Tightening of the lock screw 108 with the spine
rod 133 disposed within the spine rode receiving channel 118
results in forces being exerted by the lock screw on the upstanding
leg portions 119. Such force is exerted between the lock screw
threads 150 and the clamping body threads 124. As such, with
non-cupped threads, this force can cause the upstanding leg
portions 119 to separate (i.e., splay apart), thereby leading to
slipping, stripping, etc of the lock screw threads 150 with respect
to the clamping body threads 124. The cupped configuration of the
lock screw threads 150 and the clamping body threads 124 as
disclosed herein advantageously causes the upstanding leg portions
119 to be drawn together when force is exerted on the upstanding
leg portions 119 by the lock screw 108. Accordingly, a pedicle
screw apparatus configured with cupped lock screw threads and the
clamping body threads as disclosed herein provide for a superior
interface between a clamping body and lock screw thereof and
provide for superior structural robustness of upstanding leg
portions thereof with the lock screw tightened in place.
[0030] Referring now to FIGS. 2, 6, 7 and 8, the upper saddle 110
is engaged at a first end portion 168 thereof with the upper saddle
receiving structure 156 of the lock screw 108. The upper saddle 110
is engaged with the upper saddle receiving structure 156 in a
manner allowing the upper saddle 110 to rotate about a centerline
axis of the lock screw 108. As shown, in one embodiment, the upper
saddle receiving structure 156 includes a passage 170 through which
a mounting post 172 of the upper saddle extends, thus allowing
rotation therebetween.
[0031] Perpendicularly intersecting spine rod receiving channels
174 extend through a spine rod engaging portion 176 of the upper
saddle 110, as best shown in FIG. 7. The perpendicularly
intersecting configuration of the spine rod receiving channels 174
is configured such that an outwardly-extending spine rod engaging
structure 178 is provided between adjacent ones of the spine rod
receiving channels 174. It is disclosed herein that one function of
the spine rod engaging structure 178 is to align the upper saddle
110 to the spine rod 133. In the case where one of the spine rod
receiving channels 174 is not fully aligned with a longitudinal
axis of the spine rod 133, contact of the spine rod 133 by one of
the spine rod engaging structure 178 causes rotation of the upper
saddle 110 with respect to the spine rod 133 in response to
bringing the upper saddle 110 into contact with the spine rod 133.
As such, the upper saddle 110 will seek alignment (i.e., self
aligning) with the spine rod 133 as the upper saddle is brought
into further contact with the spine rod 133.
[0032] As best shown in FIG. 7, an upper surface 180 and a lower
surface 182 of each spine rod engaging structure 178 are acutely
angled with respect to each other and a channel edge 184 defined
between the upper and lower surfaces 180, 182 is sharply pointed.
Furthermore, the upper surface 180 of each spine rod engaging
structure 178 is downwardly contoured such that a thickness of each
spine rod engaging structure 178 is thinnest at a tip portion 184
thereof. The spine rod engaging portion 176 has a generally square
end view profile such that the channel edge 184 defined between the
upper and lower surfaces 180, 182 are generally straight in the end
view (FIG. 8). The sharply pointed configuration advantageously
serves to mechanically lock (i.e., engage) the upper saddle into
position on a respective spine rod, thus preventing unintentional
movement therebetween. Similarly, the downwardly contoured
configuration of the upper surface 180 of the spine rod engaging
structures 178, and the overall configuration of the upper saddle
110, serves to allow controlled deformation of the spine rod
engaging structures 178. Such controlled deformation further
promotes mechanically locking of the upper saddle in position on
the respective spine rod (i.e., through the sharply pointed channel
edge 184 biting into the surface of the spine rod), thus preventing
unintentional movement therebetween.
[0033] In the preceding detailed description, reference has been
made to the accompanying drawings that form a part hereof, and in
which are shown by way of illustration specific embodiments in
which the present invention may be practiced. These embodiments,
and certain variants thereof, have been described in sufficient
detail to enable those skilled in the art to practice embodiments
of the present invention. It is to be understood that other
suitable embodiments may be utilized and that logical, mechanical,
chemical and electrical changes may be made without departing from
the spirit or scope of such inventive disclosures. To avoid
unnecessary detail, the description omits certain information known
to those skilled in the art. The preceding detailed description is,
therefore, not intended to be limited to the specific forms set
forth herein, but on the contrary, it is intended to cover such
alternatives, modifications, and equivalents, as can be reasonably
included within the spirit and scope of the appended claims.
* * * * *